The present invention relates to an improved technology for a vehicle body structure of an automotive vehicle.
FIGS. 9A and 9B are conceptual drawings of a conventional vehicle body structure and show a typical example of a vehicle body 101 of a convertible or cabriolet 100.
FIG. 9A shows that the vehicle body 101 comprises a monocoque body having incorporated therein left and right side members 102, 102 and cross members (not shown) extending between these side member 102, 102. The side member 102 comprises a front side frame 103 located at a front portion of the vehicle body, a floor frame 104 located at a longitudinal center of the vehicle body and a rear side frame 105 located at a rear portion of the vehicle body, which are joined together in that order. The vehicle body 101 also has a floor tunnel 106 disposed at the center of the vehicle body. Reference numeral 107 denotes a floor panel.
FIG. 9B shows the structure of the side member 102 when viewed from the side of the vehicle body in which the floor frame 104 is disposed lower than the front and rear side frames 103, 105 so as to secure a certain dwelling performance inside a passenger compartment.
However, the vehicle 100 tends to be subject to torsional and/or bending moment while running, and the vehicle body 101 of the vehicle 100 is required to provide a sufficient rigidity. In particular, in the case of a convertible, since it has no fixed roof, an upper portion of a vehicle body thereof cannot be supported by a roof, and therefore the rigidity of the vehicle body 101 must be increased to such an extent that a decrease in rigidity due to the lack of a roof can be compensated for. In addition, the side member 102 is constructed as bent when viewed from the side thereof, and here again the rigidity of the vehicle body 101 must be increased to such an extent that a decrease in rigidity due to the bent side member can be compensated for.
In these circumstances, a number of reinforcement members 108 . . . are provided at portions of the vehicle body where an increase in rigidity is required for partial reinforcement. However, the addition of a number of reinforcement members 108 as described above results in an increase in vehicle weight, this preventing the reduction in the weight of the vehicle body 101.